The privacy of the Duchess of Cambridge is worth its weight in lead. Not gold, but lead. Her mother-in-law, Her Majesty Queen Elizabeth II, has never been photographed in a wardrobe malfunction with the royal pins – let alone the royal buttocks – on display as a result of a treacherous gust of wind. Not only does she favour more sober attire than young Kate, but she also has tiny balls of lead sewn into the hems of her dresses.

The Duchess of Cambridge’s body has been subjected to the public’s gaze ever since the eyes of her now husband had little trouble boring through her diaphanous dress as she sashayed down a university catwalk. Less happily, she was subsequently snapped by a long lens camera as she sunbathed, topless, on the private terrace of a private villa, set in acres of private land and published in the French magazine, Closer. And now, because our Duchess favours the flirty hemline of designer Diane von Furstenberg, does not favour lead in the hemline à la mother-in-law, and certainly does not favour big, sensible knickers, she faces further intrusions into her personal privacy.

These most recently exposed private royal body parts were published in the German tabloid Bild. But why were they not spread over the British tabloids? The press in Blighty has been referred to as the bloodhound and watchdog of society because it fulfils a vital role in rooting out and alerting us to wrongdoing, corruption and other ills in our society. But the role of the media hound should not extend to rooting out the underwear of royalty, or alerting us to salacious, celebrity tittle-tattle. Having, however, done the latter for years – culminating in the phone hacking scandal and the demise of the 168 year old Murdoch-owned News of the World newspaper – the feral beast was confined to the dog house and harshly chastised by Lord Leveson in his enquiry into press ethics. So has it learnt from its past misbehaviour, now acting as a good servant to its readers and obeying the rules?

The British press is still snappy when it comes to press regulation and refuses to be drawn into any form of regulation backed by statute, arguing that this involves government interference. And it is still prepared to invade privacy where it considers that it is in its interests to do so. Only last month The Daily Mail was found to be at fault by the British courts for having published photographs of the children of musician Paul Weller (of the Jam and Style Council fame) taken on a public street in Santa Monica, California.

Privacy is protected in the UK by Article 8 of the European Convention on Human Rights, which guarantees the right to respect for private and family life, home and correspondence. Historically, that has included health and medical matters, sexual and relationship issues and, when it comes to images, the naked or semi-naked body (after all, as the House of Lords said in the Naomi Campbell case – and Tele Sevalis said in the 1970s hit – a picture paints a thousand words). The test applied by the courts of England and Wales is whether the subject has a reasonable expectation of privacy with regard to the information under threat. Whether they do will depend on various factors, including where the image was taken, how it was taken (e.g. with a long lens/surreptitiously), what it depicted, how private the occasion was, the identity of the person and their relationship with the media and their own attitude to privacy. If this is established, then the courts weigh this right against any other Convention right at play which, in media cases, will usually be the Article 10 right to freedom of expression. The bare buttocks of a Duchess may be interesting to the public and thus sell magazines, but there is no public interest justification for their publication.

Was it a fear of legal reprisals then, which curtailed the British tabloids from publishing the pictures because they saw no public interest or other justification to allow that posterior to be exterior? But Catherine is the mother of the heir to the throne – undeniably a public figure used to dealing with the media; she was photographed in public and in circumstances where she knew that the cameras would be trained on her; she was wearing a not uncharacteristically flimsy and flirty dress and had presumably chosen her own underwear.

Call me cynical, but the real reason was perhaps that the desire of the tabloids to publish pictures of her bottom was surpassed only by their desire not to harm their own bottom line by outraging the royalty-loving readership. Perhaps in reality they feared a loss of sales when their readership threw down their newspapers in disgust and consigned them henceforth to the wrappings of that good old British favourite, the fish and chip supper.

On balance, I consider that the pert derriere of our Duchess is something in respect of which she does have a reasonable expectation of privacy. If it continues to be flaunted however, by default, design or Diane von Furstenberg, that expectation may become less reasonable. And she may find that the media hounds ultimately – even in Britain – put their stiff upper lips to one side and embrace the idea of providing their readers with what their European cousins are lapping up.

The moral of this story is that in today’s ever more intrusive world, we need to take care to protect ourselves. Everyone today with a mobile phone is a potential photographer; everyone with access to a computer is a potential publisher; and, with the internet, everyone with a quick pic and a mouse in their hand can be the publisher of private photographs to the world at large. So, before you go out in the morning, consider the equivalent of lead weights in the hem of your skirt and eschew places and events where you are likely to be unhappily papped. And always be aware that we are all at risk of our private life being exposed by others.

Privacy has been likened to an ice cube; give it to a person who refuses to put it in the refrigerator and it will quickly melt and lose its confidential nature altogether. For those of us who have the choice, if we can’t stand the heat of the prying eyes of the media then, in order to protect our privacy, we must stay out of the kitchen – or at least wear sensible, sturdy pants.